In our U.S. Pat. Nos. 4,994,276; 5,128,143; and 5,135,757, hereby incorporated by reference, we reported that a controlled release excipient which is comprised of synergistic heterodisperse polysaccharides (e.g., a heteropolysaccharide such as xanthan gum in combination with a polysaccharide gum capable of cross-linking with the heteropolysaccharide, such as locust bean gum) is useful in the preparation of oral solid dosage forms using either direct compression (e.g., following addition of drug and optionally lubricant powder), conventional wet granulation, or a combination of the two. The release of the medicament from the formulations therein proceeds according to zero-order or first-order mechanisms.
The sustained release excipients disclosed in U.S. Pat. Nos. 4,994,276, 5,128,143, and 5,135,757 are commercially available under the tradename TIMERx.TM. from Edward Mendell Co., Inc., Patterson, N.Y., the assignee of the present invention.
European Patent No. 234670 B (Pankhania et al.) describes a sustained release pharmaceutical formulation containing xanthan gum wherein the xanthan gum comprises from about 7.5 to about 28%, by weight, of the formulation except for a formulation wherein the sustained release carrier comprises a mixture of 15-50 parts by weight dimethylsiloxane, 30-100 parts by weight silicic acid, 30-100 parts by weight mannans or galactans or a mixture thereof, 50-150 parts by weight xanthans and 5-75 parts by weight micronized seaweed.